This invention relates to a centrifugal clutch in which the clutch is either engaged or disengaged by centrifugal action when the speed of rotation of one of the clutch members reaches a predetermined magnitude. The invention has more particular reference to a wrap spring clutch in which a helical spring wraps down against coaxial cylindrical clutch surfaces on input and output hubs to couple the latter for rotation together. One end of the spring is anchored on one of the hubs and the other end is secured to a control collar which is concentric with the clutch surfaces. In a normally engaged clutch, turning of the control collar relative to the hubs causes the spring to unwrap from the clutch surfaces and free the hubs to rotate independently of each other. In a normally disengaged clutch, turning of the control collar relative to the hubs causes the spring to wrap down on the hubs to couple the hubs for rotation in unison.